Air carrier medium large transport altitude deviation excursion from clearance altitude.

Attributes
ACN	100511
Time
Date	198812
Day	Thu
Local Time Of Day	0601 To 1200
Place
Locale Reference	atc facility : atr
State Reference	DE
Altitude	msl bound lower : 15000 msl bound upper : 16000
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	artcc : zdc
Operator	common carrier : air carrier
Make Model Name	Medium Large Transport, Low Wing, 2 Turbojet Eng
Flight Phase	descent other
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : commercial pilot : instrument
Experience	flight time last 90 days : 50 flight time total : 7000 flight time type : 1000
ASRS Report	100511
Person 2
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : atp
Events
Anomaly	altitude deviation : crossing restriction not met altitude deviation : overshoot non adherence : clearance
Independent Detector	other controllera
Resolutory Action	other
Consequence	Other
Supplementary
Primary Problem	Ambiguous
Air Traffic Incident	Operational Deviation Pilot Deviation

Narrative:

We were given a clearance to 'descend to cross ATR at 16000'', then maintain 14000'. Due to the manner in which the controller issued the clearance, both the captain and I interpreted the clearance as 'cross ATR at 16000, maintain 14000'.' about 4 mi north of the VOR we passed 15000' and the controller clarified his clearance, stressing the word 'then'. No conflict existed and the controller told us not to worry about it. Both the captain and I were surprised that we both could have missed the 'then' portion of the clearance, but perhaps we became a bit too complacent with this regular route into washington, dc. In the future we'll not only verify our clearance, but our readbacks as well. Thanks for your time.

Original NASA ASRS Text

Title: ACR MLG ALT DEVIATION EXCURSION FROM CLRNC ALT.

Narrative: WE WERE GIVEN A CLRNC TO 'DSND TO CROSS ATR AT 16000'', THEN MAINTAIN 14000'. DUE TO THE MANNER IN WHICH THE CTLR ISSUED THE CLRNC, BOTH THE CAPT AND I INTERPRETED THE CLRNC AS 'CROSS ATR AT 16000, MAINTAIN 14000'.' ABOUT 4 MI N OF THE VOR WE PASSED 15000' AND THE CTLR CLARIFIED HIS CLRNC, STRESSING THE WORD 'THEN'. NO CONFLICT EXISTED AND THE CTLR TOLD US NOT TO WORRY ABOUT IT. BOTH THE CAPT AND I WERE SURPRISED THAT WE BOTH COULD HAVE MISSED THE 'THEN' PORTION OF THE CLRNC, BUT PERHAPS WE BECAME A BIT TOO COMPLACENT WITH THIS REGULAR ROUTE INTO WASHINGTON, DC. IN THE FUTURE WE'LL NOT ONLY VERIFY OUR CLRNC, BUT OUR READBACKS AS WELL. THANKS FOR YOUR TIME.

Data retrieved from NASA's ASRS site as of August 2007 and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.